Immobilization of camptothecin with surfactant into hydrogel for controlled drug release

A new strategy has been developed for the controlled release of a hydrophobic anticancer drug, camptothecin (CPT), which suffers a limited therapeutical utility because of its poor water solubility. CPT was first solubilized in the solution of a cationic surfactant, dodecyltrimethylammonium bromide (DTAB). It has been demonstrated that the presence of DTAB has increased the solubility of CPT significantly. In a 50 mM DTAB solution, the drug’s solubility was enhanced to 85 μM, 22 times of its solubility in pure water. The micellar drug solution of CPT-DTAB was subsequently used to prepare agarose hydrogels, which act as the drug carriers in the release studies. To fully take advantage of the cationic property of DTAB, negatively charged κ-carrageenan was added as a guest polymer in some hydrogel samples. The release of CPT from these hydrogel-surfactant systems was performed at 37 °C and the effects of DTAB and κ-carrageenan on the release of CPT were studied respectively. By fitting to the well-known Fickian diffusion model, the diffusion coefficients of CPT were obtained.